Feedthrough connectors in glass

Abstract

A feedthrough connector contains an electrically insulating body formed from glass. The body has a front side and a back side facing away from the front side. The body further has a circumferential lateral side extending from the front side to the back side of the body. The body has a plurality of through-openings, wherein each through-opening extends from the front side to the back side of the body. A plurality of electrical conductors is provided and, each conductor is arranged in one of the through-openings to hermetically seal the respective through-opening. The respective conductor contains a metallic material. A first end of the conductor is arranged at the front side and is connected to a first contact pad arranged on the front side, and an opposing second end is arranged at the back side and is connected to a second contact pad arranged on the back side. A method for producing the feedthrough connector includes to provide blind holes in the body with metallic material filled into the blind holes to define conductors.

Claims

1. A method for producing a feedthrough connector, which comprises the steps of: providing a glass wafer having at least one wafer portion, the at least one wafer portion having a front side and a back side facing away from the front side; forming a plurality of blind holes and a circumferential recess in the front side of the at least one wafer portion such that the circumferential recess surrounds the blind holes; filling a metallic material into the blind holes of the at least one wafer portion to form conductors, wherein each of the conductors having a first end at the front side of the at least one wafer portion and a second end at a bottom of each of the blind holes; and filling a further metallic material into the circumferential recess of the at least one wafer portion to form a flange of the at least one wafer portion.

2. The method according to claim 1, which further comprising: applying a coating to an inner side of a respective blind hole of the at least one wafer portion before the metallic material is filled into the blind holes of the at least one wafer portion; and/or applying a coating to an inner side of the circumferential recess of the at least one wafer portion before the further metallic material is filled into the circumferential recess of the at least one wafer portion.

3. The method according to claim 1, which further comprises: masking the front side of the at least one wafer portion with a mask such that the first end of the conductors at the front side of the at least one wafer portion are not covered by the mask; depositing a further metallic material on non-covered first ends of the conductors to form first contact pads; and removing the mask from the front side of the at least one wafer portion after forming the first contact pads.

4. The method according to claim 1, which further comprises removing a layer on the back side of the at least one wafer portion so as to expose the second end of the conductors of the at least one wafer portion.

5. The method according to claim 1, which further comprises forming a plurality of holes in the back side of the at least one wafer portion, wherein each of said holes is disposed offset with respect to an associated one of the blind holes formed in the front side of the at least one wafer portion, such that a respective hole exposes a portion of a conductor in an associated blind hole, and filling the metallic material into the holes in the back side of the at least one wafer portion to form a narrowing of a respective conductor and to prolong the respective conductor such that it extends with the second end towards the back side of the at least one wafer portion.

6. The method according to claim 4, which further comprises: masking the back side of the at least one wafer portion with a mask such that the second end of a respective conductor at the back side of the at least one wafer portion is not covered by the mask, and wherein a further metallic material is deposited on a non-covered second end of the respective conductor to form a second contact pad connected to the respective conductor; and removing the mask from the back side of the at least one wafer portion after forming second contact pads.

7. The method according to claim 1, which further comprises mounting the glass wafer on a carrier.

8. The method according to claim 1, which further comprises removing a region of the at least one wafer portion that surrounds the flange of the at least one wafer portion so that a circumferential lateral side of the flange of the at least one wafer portion is exposed and a remaining portion of the at least one wafer portion forms an electrically insulating body of the feed through connector resting on the carrier.

9. The method according to claim 1, wherein the at least one wafer portion is one of a plurality of wafer portions connected to each other.

10. The method according to claim 7, wherein the front side of the at least one wafer portion is disposed on the carrier.

11. A feedthrough connector, comprising: an electrically insulating body formed out of glass, said electrically insulating body having a front side and a back side facing away from said front side, said electrically insulating body further having a circumferential lateral side extending from said front side to said back side of said electrically insulating body, and said electrically insulating body having a plurality of through-openings formed therein, each of said through-openings extending from said front side to said back side of said electrically insulating body, each of said through-openings defined by a respective first hole segment from front side into said body and a respective second hole segment from backside into said body axially, said respective first hole segment being offset from said respective second hole segment for defining a narrowing of said through-openings; first contact pads; second contact pads; a plurality of electrical conductors, each of said electrical conductors disposed in one of said through-openings such that each of said through-openings is hermetically sealed, wherein a respective conductor of said electrical conductors having a metallic material, said respective conductor having a first end disposed at said front side and connected to one of said first contact pads disposed on said front side, and an opposing second end disposed at said back side and connected to one of said second contact pads disposed on said back side; and a circumferential flange having a further metallic material, wherein said circumferential flange is connected to said circumferential lateral side of said electrically insulating body such that said circumferential flange surrounds said electrically insulating body and contacts said circumferential lateral side of said electrically insulating body.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 is a schematical plan view onto a front side of a feedthrough connector according to the present invention;

(2) FIG. 2 is a schematical cross sectional view of the feedthrough connector shown in FIG. 1;

(3) FIG. 3 is an illustration of a glass wafer that can be used to produce multiple feedthrough connectors of the kind shown in FIGS. 1 and 2 in a parallel fashion;

(4) FIG. 4 is a schematical plan view onto a wafer portion of the glass wafer shown in FIG. 3 after forming blind holes and a circumferential recess into a front side of the wafer portion;

(5) FIG. 5 is a schematical cross sectional view of the wafer portion shown in FIG. 4;

(6) FIG. 6 is a schematical plan view onto the wafer portion of FIGS. 4 and 5 after filling of the blind holes and the recess with a metallic material to form conductors and a flange;

(7) FIG. 7 is a schematical cross section view of the wafer portion shown in FIG. 6;

(8) FIG. 8 is a schematical plan view of first contact pads on first ends of the conductors;

(9) FIGS. 9 to 11 are schematical cross section views showing the forming of the first contact pads on the first ends of the conductors;

(10) FIG. 12 is a schematical plan view showing the forming of the first contact pads on the first ends of the conductors;

(11) FIGS. 13A to 13B are plan views for show the forming of second contact pads on the second ends of the conductors;

(12) FIGS. 14A to 14B are schematical cross section views showing the forming of second contact pads on the second ends of the conductors;

(13) FIG. 15 is a plan view for forming the second contact pads on the second ends of the conductors;

(14) FIG. 16 is a schematical cross section view showing the forming of second contact pads on the second ends of the conductors;

(15) FIG. 17 is an illustration showing a mounting of the glass wafer onto a carrier;

(16) FIGS. 18 to 21 are illustrations for showing the step of releasing the flanges and thereby separating of the individual feedthrough connectors;

(17) FIGS. 22 to 23 are illustrations showing the carrier with the separated feedthrough connectors arranged thereon;

(18) FIGS. 24 to 25 are illustrations showing the connecting of a feedthrough connector to an electrical circuit and a housing of an implantable medical device; and

(19) FIGS. 26 to 27 are schematical cross section views showing an alternative way of forming conductors in the respective wafer portion/electrically insulating body of the respective feedthrough connector.

DETAILED DESCRIPTION OF THE INVENTION

(20) Referring now to the figures of the drawings in detail and first, particularly to FIGS. 1 and 2 thereof, there is shown an embodiment of a feedthrough connector 1 according to the present invention. The feedthrough connector 1 comprises an electrically insulating body 2 formed out of a glass, wherein the body 2 further comprises a front side 2a and a back side 2b that faces away from the front side 2a, wherein the body 2 further comprises a circumferential lateral side 2c extending from the front side 2a to the back side 2b of the body 2. The body/insulator 2 further comprises a plurality of through-openings 40, wherein each through-opening 40 extends from the front side 2a to the back side 2b of the body 2, and a corresponding plurality of electrical conductors 4, wherein each conductor 4 is arranged in one of the through-openings 40 such that the respective through-opening 40 is hermetically sealed. The respective conductor 4 comprises a metallic material, a first end 4a arranged at the front side 2a and connected to a first contact pad 5 arranged on the front side 2a, and an opposing second end 4b arranged at the back side 2b and connected to a second contact pad arranged 6 arranged on the back side 2b. Furthermore, the feedthrough connector 1 comprises a circumferential flange 3 comprising a further metallic material, wherein the flange 3 is connected to the lateral side 2c of the body 2 such that the flange 3 surrounds the body 2 and contacts the lateral side 2c of the body 2.

(21) As shown in FIG. 2, the flange 3 can cover the entire lateral side 2c of the electrically insulating body 2 of the connector 1.

(22) According to an embodiment of the feedthrough connector 1 shown in FIGS. 26 and 27 (see also below), the respective through-opening 40 of the connector 1 can comprise a first section 40a starting at the front side 2a of the body 2 and connected to a second section 40b extending to the back side 2b of the body 2 (cf. FIG. 26). The first and the second sections 40a, 40b of the respective through-opening 40 are arranged offset with respect to one another so that the respective through-opening 40 comprises a narrowing 401, wherein the flange 3 particularly covers a circumferential section 2cc of the lateral side 2c, which section 2cc comprises a height H.sub.cc corresponding to a length V.sub.40a (in a direction perpendicular to the front side 2a and/or back side 2b) of the first section 40a of the respective through-opening 40 (cf. FIG. 26). Alternatively however, the flange could extend along the entire length height V.sub.h of the wafer.

(23) For forming the conductors 4, the first and second contact pads 5, 6 as well as the flanges the metallic materials described herein can be used.

(24) Further, particularly, the first contact pads 5 on the front side 2a of the body 2 are configured to be arranged outside a housing 12 of an implantable medical implant device 11, and/or the second contact pads 6 on the back side 2b of the body 2 are configured to be connected to an electrical circuit 13 enclosed by the housing 12, which circuit can be arranged on a substrate 14 such as a printed circuit board. The feedthrough connector 1 thus provides electrical connection between the electrical circuit 13 and a component (such as a header) arranged outside the housing 12.

(25) As indicated in FIG. 2, according to an embodiment of the present invention, the body 2 can comprise a height V.sub.h corresponding to a distance between the front side 2a and the back side 2b of the body 2 that is in the range from 0.3 mm to 1.5 mm.

(26) Furthermore, as indicated in FIG. 1, according to an embodiment of the present invention, a minimal distance D.sub.m of the respective first contact pad 5 to an edge of the front side 2a of the body 2 is in the range from 0.25 mm to 1.0 mm. Further, according to an embodiment, a minimal distance D′.sub.m of the respective second contact pad 6 to an edge of the back side 2b of the body 2 is in the range from 0.25 mm to 1.0 mm.

(27) Further, as indicated in FIG. 2, in an embodiment, the flange 3 can comprise a thickness F.sub.d in a direction normal to the lateral side 2c of the flange 3 that is in the range from 0.2 mm to 3.0 mm.

(28) Further, as indicated in FIG. 5, according to an embodiment, the flange 3 comprises a height F.sub.h in a direction along which the respective conductor 4 extends between the front side 2a and the back side 2b of the body 2 (or in a direction perpendicular to the front side 2a and/or back side 2b of the body 2) that is in the range from 0.3 mm to 1.5 mm.

(29) Furthermore, in an embodiment, the respective first contact pad 5 can comprise a thickness C.sub.h in a direction normal to the front side 2a of the body 2 that is in the range from 0.05 mm to 0.5 mm (cf. FIG. 2). Further, in an embodiment, the respective second contact pad 6 can comprise a thickness C′.sub.h in a direction normal to the back side 2b of the body 2 that is in the range from 0.05 mm to 0.5 mm (cf. FIG. 2).

(30) Furthermore, in an embodiment, the respective first contact pad 5 can comprise a width C.sub.w in a direction parallel to the front side 2a of the body 2 that is in the range from 0.1 mm to 1 mm (cf. FIG. 2). Likewise, in an embodiment, the respective second contact pad 6 can comprise a width C′.sub.w in a direction parallel to the back side 2b of the body 2 that is in the range from 0.1 mm to 1 mm (cf. FIG. 2).

(31) Furthermore, according to an embodiment, the respective conductor 4 can comprise a length (e.g. in the direction of the height of the body 2) V.sub.h as indicated in FIG. 2 that is in the range from 0.5 mm to 1.5 mm (corresponding e.g. to the height V.sub.h of the body 2 and of the flange 3).

(32) Furthermore, in an embodiment, as indicated in FIG. 4, the respective conductor 4 can comprise a diameter V.sub.d, particularly perpendicular to the length V.sub.h of the respective conductor 4 or perpendicular to the height V.sub.h of the body 2 and/or flange 3 that is in the range from 0.01 mm to 0.5 mm.

(33) Particularly, the individual dimensions of the feedthrough connector 1 stated above can be combined in any reasonable manner.

(34) Particularly, the feedthrough connector 1 shown in FIGS. 1 and 2 can be produced using a method according to the present invention which shall be described in more detail below.

(35) According to the method, a glass wafer 100 (e.g. circular wafer having diameter in the range from e.g. 100 mm to 300 mm) is provided as shown in FIG. 3, which comprises a plurality of adjacent wafer portions 10, wherein each wafer portion 10 comprises a front side 10a and a back side 10b facing away from the respective front side.

(36) The respective wafer portion 10 will form the body 2 of the respective final feedthrough connector 1 and will be provided with conductors 4, contact pads 5, 6 and a flange during the process.

(37) As further indicated in FIGS. 4 and 5 a plurality of blind holes 40 are formed in the front side 10a of the respective wafer portion 10 and a circumferential recess 30 such that the recess 30 surrounds the blind holes 40. Particularly, the blind holes 40 and/or the recess 30 of the respective wafer portion 10 can have e.g. a depth V.sub.h in the range from 50% to 95% of the glass wafer's 100 height in a direction perpendicular to the respective front side 2a or back side 2b (see also above).

(38) After forming of the blind holes 40/recess 30, a metallic material is arranged in the blind holes 40 of the respective wafer portion 10 to form conductors 4, so that each conductor 4 comprises a first end 4a at the front side 10a of the respective wafer portion 10 and a second end 4b at a bottom of the respective blind hole 40. A further metallic material is filled in the recess 30 of the respective wafer portion 10 to form a flange 3 of the respective wafer portion 10. This is indicated in FIGS. 6 and 7. Particularly, the metallic material and the further metallic material can be identical.

(39) Particularly, the blind holes 40 and/or the respective recess 30 in the front side 10a of the respective wafer portion 10 can be formed by patterning the front side 10a of the respective wafer portion 10 with a photoresist (PR) followed by a dry etching process such as e.g. RIE (reactive ion etching). Alternatively, inductive coupled plasma (ICP) or ion milling can be used. As a further alternative, the blind holes 40 and/or the recess 30 of the respective wafer portion 10 can also be formed using a laser.

(40) To improve adhesion of the metallic material filled into the blind hole or of the further metallic material filled into the recess of the respective wafer portion 10, a coating 42 can be applied to an inner side 41 of the respective blind hole 40 of the respective wafer portion 10 before the metallic material is filled in the blind holes 40 of the respective wafer portion. Correspondingly, such a coating 32 can be applied to an inner side 31 of the recess 30 of the respective wafer portion 10 before the further metallic material is filled in the recess 30 of the respective wafer portion 10. Particularly, the coating 42, 32 of the inner sides 41, 31 of the blind holes 40 or of the recesses 30 can be a metallization process. Such a metallization 42, 32 can comprise one or a combination of Ti, Ta, an alloy comprising Ti and W, Ni (e.g. in form of a Ni seed layer). The respective coating 42, 32 can be applied by way of suitable methods such as physical vapor deposition (PVD), sputtering, or evaporation. The thickness of the respective coating/metallization 42, 32 can be in the range from e.g. 0.1 μm to 1 μm.

(41) Furthermore, the blind holes 40 and/or the recess 30 of the respective wafer portion 10 can be filled (e.g. after applying the coatings 32, 42) with the respective metallic material by a CVD process (depositing of e.g. one of W, Ni, Ti), or by plating (e.g. Ni).

(42) After filling of the blind holes 40/recess 30, the front side 10a of the respective wafer portion 10 can be planarized, if necessary, by way of suitable methods (e.g. CMP).

(43) In order to form first contact pads 5 on the front side 10a of the respective wafer portion 10, the front side 10a of the respective wafer portion can be covered by a mask 50 as shown in FIGS. 8 and 9 such that the first ends 4a of the conductors 4 at the front side 10a of the respective wafer portion 10 are not covered by the mask 50. Then, as shown in FIG. 10 a further metallic material can be deposited on the non-covered first ends 4a of the conductors 4 (through holes 51 of the mask 50) to form the first contact pads 5. Afterwards, as shown in FIG. 11, the mask 50 can be removed from the front side 10a of the respective wafer portion 10 which now comprises the first contact pads 5 formed on the conductors 4 as shown in FIGS. 11 and 12. Particularly, the first contact pads 5 can be formed out of a metal such as e.g. one or a combination of Au, Pt, Nb, Ti, that can be evaporated or sputtered onto the first ends 4a of the conductors 4 through the holes 51 in the mask 50.

(44) In order to also form second contact pads on the back side 10b of the respective wafer portion 10, a first variant of the method can be conducted, wherein a layer on the back side 10b of the respective wafer portion 10 is removed by back-grinding or CMP, as shown in FIGS. 13A and 13B as well as FIGS. 14A and 14B so as to expose the second ends 4b of the conductors 4 of the respective wafer portion 10.

(45) Alternatively, according to a second variant, which is shown in FIGS. 26 and 27, a plurality of holes 400 can be formed in the back side 10b of the respective wafer portion 10 instead, wherein each of the holes 400 is arranged offset with respect to an associated blind hole 40 formed in the front side 10a of the respective wafer portion (as described above), such that the respective hole 400 exposes a portion of the conductor 4 in the associated blind hole 40. Then, the metallic material used for forming the conductors 4 is deposited in the newly formed holes 400 in the back side 10b of the respective wafer portion 10 to form a narrowing 401 of the respective conductor 4 and to prolong the respective conductor 4 such that it extends with its second end 4b up to the back side 10b of the respective wafer portion 10 as indicated in FIG. 27. Also here, a coating can be applied to an inner side of the respective hole 400 (using e.g. one of the materials stated with respect to the coating 42 of the blind holes 40) before the metallic material is filled into the holes 400.

(46) Now, in order to form second contact pads 6 on the second ends 4b of the conductors 4 as shown in FIGS. 15 to 16 again a mask can be used as in case of the first contact pads 5. Also here, a mask is arranged on the back side 10b of the respective wafer portion 10 such that the second end 4b of the respective conductor at the back side 10b of the respective wafer portion 10 is not covered by the mask (not shown). Then, a further metallic material is deposited on the non-covered second end 4b of the respective conductor 4 to form a second contact pad 6 thereon. After forming of the second contact pads 6 the mask is removed from the back side 10b of the respective wafer portion 10. The further metallic material for the second contact pads 6 can comprise or can be formed by the materials stated above with respect to the second contact pads 6. Particularly, this further metallic material can comprise or can be one of the following (e.g. solderable) metals: Sn/Ni, Cu/Ni, Sn/Pb, Pt, Rh, Nb, an alloy comprising Sn, Ag, and Cu.

(47) In order to separate the individual wafer portions 10 from one another and exposing the flange so as to produce the final feedthrough connectors 1 each comprising an electrically insulating body 2 formed from the respective wafer portion 10, the glass wafer 100 (i.e. the connected wafer portion 10) is mounted on a carrier 200 as shown in FIG. 17, wherein particularly the front side 10a of the respective wafer portion 10 is arranged on the carrier 200.

(48) Particularly, exposing the flange and separation of the wafer portions 10 from one another can be conducted as shown in FIGS. 18 to 21 by removing a region 10c of each wafer portion 10 that surrounds the flange 3 of the respective waver portion 10 so that a circumferential lateral side 3c of the flange 3 of the respective wafer portion 10 is exposed and the remaining portion 2 of the respective wafer portion 10 forms the electrically insulating body 2 of the respective feed through connector 1 resting on the carrier 200.

(49) Particularly, as shown in FIG. 18, for separating the wafer portions 10 from one another, a mask 60 can be arranged on the back side 10b of each carrier portion 10, which mask 60 extend on the back side 10b of the respective wafer portion 10 up to an outer edge of the flange 3 of the respective wafer portion 10 so that the region 10c of the respective wafer portion 10 is not covered by the mask 60. Particularly, the mask's protective metal can be formed by Ni or Al metal layers highly selective to dry etch chemistry. Alternatively, conventional lithography can be used to deposit a mask such as SU8 on the back side 10b of the respective wafer portion 10.

(50) After positioning of the mask 60, the region 10c of the respective wafer portion 10 is removed by way of etching using e.g. a RIE dry etching process. Alternatively, the region 10c of the respective wafer portion 10 can be removed by means of a laser to separate the wafer portions 10/feedthrough connectors 1 from one another. Particularly, such a laser based singulation can be followed by a wet or dry chemical process to remove residual glass and expose the flange 3 of the respective wafer portion 10/feedthrough connector 1.

(51) After separating the individual wafer portions 10, a corresponding plurality of feedthrough connectors 1 rest on the carrier 200 as indicated in FIGS. 22 and 23. The individual feedthrough connector 1 can now be mounted to a device such as an implantable medical device 11 as shown in FIGS. 24 and 25.

(52) Particularly, according to FIG. 24, the second contact pads 6 are connected, particularly welded or soldered, to corresponding contacts of an electrical circuit 13 of the medical device 11 which circuit can be arranged on a substrate 14 (e.g. printed circuit board).

(53) Furthermore, the flange 3 of the feedthrough connector 1 is welded in a hermetically sealed fashion to a housing 12 of the medical device 11. The feedthrough connector now provides a hermetically sealed interface for making electrical connections to the circuit 13 via the first contact pads 5 being arranged outside of the housing. For instance, the implantable medical device 11 can be an implantable cardiac pacemaker and the feedthrough connector 1 can provide electrical connections to a header of the pacemaker 11.

(54) It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teaching. The disclosed examples and embodiments are presented for purposes of illustration only. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention.